Porous solids, selective separations, removal of sulfur compounds, adsorption

ABSTRACT

Crystals of [VOBDC](H 2 BDC) 0.71  were synthesized hydrothemally. The guest acid molecules were removed by heating in air to give high quality single crystals of VOBDC. VOBDC was observed to show crystal-to-crystal transformations on absorption of the guest molecules aniline, thiophene and acetone from the liquid phase. Accurate structural data of the guest molecules and framework deformations were obtained from single crystal X-ray data. VOBDC was also shown to absorb selectively thiophene and dimethyl sulphide from methane.

RELATED APPLICATIONS

This application claims priority to and the benefit of PCT ApplicationSerial No. PCT/US07/17729, filed 9 Aug. 2007 (Aug. 9, 2007), whichclaims priority to and the benefit of U.S. Provisional PatentApplication Ser. No. 60/836,806 filed 10 Aug. 2006 (Aug. 10, 2006).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a class of porous metal organicmaterials has novel selective adsorption characteristics and for methodsof making and using same.

More particularly, the present invention relates to a class of porousmetal organic materials has novel selective adsorption characteristics,where materials are based on trans linked chains of metal oxygenoctahedra that are cross-linked by aromatic dicarboxylic acids and formethods of making and using same.

2. Description of the Related Art

Many applications of nanoporous materials such as molecular sieving, ionexchange and functional nanocomposites are based on specificinteractions between the host frameworks and removable guest species.The capacity and selectivity of nanoporous materials in absorption andin separation of molecular mixtures depend on specific interactionsbetween the host frameworks and removable guest species and in somecases the degree to which the structure of the host lattice can relax asmolecular species are intercalated. Detailed structural data arecritical to understand these interactions.

The classical zeolite frameworks are relatively rigid and exhibit littledeformation upon loading and unloading of various guest species.¹ On theother hand, intercalation into layered structures leads to expansion ofthe interlayer separation because of the very weak interlayer bonding,and can lead to complete exfoliation of the layers.²

Variable flexibilities without loss of crystallinity are expected forstructures containing rigid building blocks linked by relativelydeformable hinge-like units. Examples of framework flexibility have beenfound in a number of metal-organic frameworks (MOFs).³ Among them, agroup of compounds first reported by Férey and coworkers,⁴ based onchains of trans corner-sharing octahedra MO₆ (M=V,⁴ Cr,⁵ Al,⁶ Fe,⁷ In⁸)cross-linked by 1,4-benzene dicarboxylate (BDC) upon removal orabsorption of guest species show remarkable framework flexibility. Thefirst member of the group [V(OH)BDC](H₂BDC)_(x) was designated as MIL-47as.⁴ The guest H₂BDC molecules are removed on heating in air and the V³⁺ions are oxidized to V⁴⁺ without changing the framework topology. Theproduct, VOBDC (designated MIL-47) was observed to absorb differentsmall guest molecules. No structural information on the absorbed guestmolecules is available although the structure of MIL-47 was solved fromsingle crystal data.⁴

Sorption studies of these metal organic frameworks have focused on H₂adsorption,⁹ but some studies of the absorption of CO₂ ¹⁰ and CH₄ ¹¹have been reported. Of particular relevance to this work is the paper byFérey and coworkers on the adsorption of CH₄ and CO₂ by MOHBDC (M=Cr,Al) and VOBDC.^(11a) The V(IV) phase VOBDC shows some differences in theabsorption isotherms compared with the trivalent compounds, but theamounts of CO₂ adsorbed above 10 bar are comparable. The relatively weakenthalpy of adsorption suggested that VOBDC has no specific adsorptionsites for CO₂.^(11a)

Thus, there is a need in the art for improved absorbants or absorbents,especially for sulfur containing compounds.

SUMMARY OF THE INVENTION

The present invention provides a class of porous metal organic materialshas novel selective and reversible adsorption characteristics. Thematerials are based on trans linked chains of metal oxygen octahedrathat are cross-linked by aromatic dicarboxylic acids. The materialscontain diamond shaped channels that permit access of aromatic and othermolecules. The general composition can be written as MOADA, where M is atetravalent metal or a mixture of tetravalent metals, O is an oxygenatom, and ADA is an aromatic dicarboxylic acid dianion (H₂ADA). Theinventors have found that MOADA compounds selectively and reversiblyadsorb sulfur-containing components of fluids (gases or liquids), suchas hydrocarbon fluids, resulting in the selective reduction of aconcentration of sulfur-containing components in the hydrocarbon fluids.In the case of gaseous fluids, the inventors have found that theabsorbents operate effectively at a total pressure of 1 atmosphere atambient temperature. The absorbents, therefore, are suitable fordesulfurizing any fluid, gas or liquid, especially hydrocarbon fluids.The inventors believe that the absorbents are better suited forhydrocarbon fluids having relatively low viscosity as use of theabsorbents with higher viscosity fluids may result in unacceptable fluidlosses.

A specific example is the compound VOBDC, where V is vanadium, O is anoxygen atom, and BDC is benzenedicarboxylate, the dianion of benzenedicarboxylic acid (H₂BDC). VOBDC has been found to selectively andreversibly adsorb thiophene from octane, a separation that indicatespotential use for sulfur removal from hydrocarbon fluid such as diesel,gasoline or the like. VOBDC also been found to selectively andreversibly adsorb sulfur compounds such as dimethyl sulfide andthiophene from methane or ethane at a total pressure of 1 atmosphere atambient temperature.

The present invention provides a method for removing sulfur from afluid, including the step of contacting the fluid with an effectiveamount of at least one absorbent of the general formula MOADA, where Mis a tetravalent metal or a mixture of tetravalent metals, O is anoxygen atom and ADA is an aromatic dicarboxylic acid dianion, where theeffective amount is sufficient to reduce a concentration ofsulfur-containing components in the fluid or to reduce a concentrationof sulfur-containing components in the fluid to desired lowerconcentrations. The process can also include the step of removing theabsorbent from the fluid and heating the absorbent to recover theabsorbed sulfur-containing components regenerating the absorbent. Theprocess can include repeating the steps of contacting, removing andregenerating on intermittent, periodical, semi-continuous or continuousbasis.

The present invention provides a system including at least one vesselcontaining at least one absorbent of this invention. The system alsoincludes a source of a fluid including sulfur-containing components. Thesystem also includes piping and valves sufficient to connect the vesselto the source of the fluid. The system is adapted to remove thesulfur-containing components in the fluid or reduce concentration of thesulfur-containing components in the fluid, when the fluid is broughtinto contact with the absorbent. If the absorbent is in a column, then aresidence time of the fluid in the column, a temperature of the columnand a pressure of the column can be adjusted to achieve a givenreduction in sulfur-containing components in the fluid.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be better understood with reference to the followingdetailed description together with the appended illustrative drawings inwhich like elements are numbered the same.

FIGS. 1A-H depict the structures of: (A) [VOBDC] 0.7(C₈H₆O₄), 1; (B,C)[VOBDC](aniline), 3; (D,E) [VOBDC](thiophene)_(0.91), 4; (F,G)[VOBDC](acetone), 5, and (H) a collection of images of 1, 2, 3 and 4 forcomparison purposes.

FIG. 2 is a plot of thiophene uptake by VOBDC from methane saturatedwith thiophene at ambient temperature. The temperature profile is shownin the top panel and the corresponding weight change in the bottompanel. The inset shows an expanded view of the thiophene uptakekinetics. The right panel shows a second experiment in which a samplesaturated with thiophene at ambient is heated to 150° C. (blue data).

FIG. 3 depicts the structure of Al(OH)(C₈H₄O₄)0.7(C₈H₆O₄), 1.

FIG. 4 is a plot of dimethyl sulfide absorption data.

FIG. 5 is a plot of thiophene absorption data.

FIG. 6 is a plot of thiophene absorption data.

FIG. 7 is a plot of toluene absorption data.

FIG. 8 is a plot of octane absorption data.

FIG. 9 is a plot of thiophene absorption data from octane.

FIG. 10 is a plot of thiophene absorption data from octane.

FIG. 11 depicts an embodiment of a batch system for desulfurizing afluid using an absorbent of this invention.

FIG. 12 depicts an embodiment of a semi-continuous or continuous systemfor desulfurizing a fluid using an absorbent of this invention.

FIG. 13 depicts an embodiment of a fluid bed system for desulfurizing afluid using an absorbent of this invention.

FIG. 14 depicts an embodiment of a moving bed system for desulfurizing afluid using an absorbent of this invention.

FIG. 15A depicts an embodiment of a gas cartridge for desulfurizing agas using an absorbent of this invention.

FIG. 15B depicts an embodiment of a fuel cartridge for desulfurizing afuel using an absorbent of this invention.

DETAILED DESCRIPTION OF THE INVENTION

The inventors have found that a new class of absorbant or absorbentmolecules can be constructed and that the new absorbants or absorbentscan be used to reduce the content of sulfur-containing compounds in afluid such as hydrocarbon fluids, e.g., chemicals, refinery streams,fuels, oils, lubricants, natural gas, crude natural gas (sour gas), orother hydrocarbon fluids including such components.

The present invention broadly relates to absorbents of the generalformula MOADA, where M is a tetravalent metal or a mixture oftetravalent metals, O is an oxygen atom and ADA is an aromaticdicarboxylic acid dianion.

The present invention broadly relates to a method for removing sulfurfrom a fluid, including the step of contacting the fluid with aneffective amount of at least one absorbent of the general formula MOADA,where M is a tetravalent metal or a mixture of tetravalent metals, O isan oxygen atom and ADA is an aromatic dicarboxylic acid dianion, wherethe effective amount is sufficient to reduce a concentration ofsulfur-containing components in the fluid or to reduce a concentrationof sulfur-containing components in the fluid to desired lowerconcentrations. The process can also include the step of removing theabsorbent from the fluid and heating the absorbent to recover theabsorbed sulfur-containing components regenerating the absorbent. Theprocess can include repeating the steps of contacting, removing andregenerating on intermittent, periodical, semi-continuous or continuousbasis.

The present invention broadly relates to a system including at least onevessel containing at least one absorbent of this invention. The systemalso includes a source of a fluid including sulfur-containingcomponents. The system also includes piping and valves sufficient toconnect the vessel to the source of the fluid. The system is adapted toremove the sulfur-containing components in the fluid or reduceconcentration of the sulfur-containing components in the fluid, when thefluid is brought into contact with the absorbent. If the absorbent is ina column, then a residence time of the fluid in the column, atemperature of the column and a pressure of the column can be adjustedto achieve a given reduction in sulfur-containing components in thefluid. Generally, when a column is used, there are at least two columns.While one column is desulfurizing the other column is regenerating. Ofcourse, the system can include a number of columns with appropriatepiping and valves to permit desulfurization and regeneration on acontinuous or semi-continuous basis. If the system is batch, then abatch of fluid is contact with an amount of absorbent in an appropriatevessel under conditions to reduce the sulfur-containing components to adesired lower value. The conditions include at least residence time ofthe fluid in the vessel, the temperature of the vessel and the pressureof the vessel. For continuous system, the absorbent is fed into a fluidbed vessel or a moving bed vessel, where absorbent is continuouslyremoved, regenerated and supplied to the vessel.

The present invention broadly relates to a disposable sulfur absorbentfor purifying case including an inline cartridge including at least oneabsorbent of this invention, where the cartridge is adapted to be placedin a transfer line between a fluid source and the fluid destination. Thecartridge can also includes a means for identifying when the absorbentmust be regenerated.

Suitable Reagents

Suitable metals for use in the MOADA absorbents of this inventioninclude, without limitation, aluminum (Al), vanadium (V), chromium (Cr),iron (Fe), titanium (Ti), zirconium (Zr), hafnium (Hf), cerium (Ce), ormixtures thereof.

Suitable dicarboxylic acids include, without limitation, any aryl oralkaryl dicarboxylic acid. Exemplary examples include, withoutlimitation, 1,4-benzene dicarboxylic acid (terephthalic acid),1,3-benzene dicarboxylic acid (isophthalic acid), 4,4′-diphenyldicarboxylic acid, 2,5-pyridine dicarboxylic acid, 1,4-naphthylenedicarboxylic acid, 1,5-naphthylene dicarboxylic acid, other rigid aryldicarboxylic acids or mixtures thereof.

Suitable fluids include, without limitation, any gas, liquid or mixturesor combinations thereof including undesirable levels ofsulfur-containing components. Exemplary fluids include, withoutlimitations, water, sewer gas, hydrogen gas, syngas, chemical gasesand/or liquids, hydrocarbon gases and/or liquids, biological gasesand/or liquids, biochemical gases and/or liquids, any other gas and/orliquid containing undesirable levels of sulfur-containing components ormixtures or combinations thereof. Exemplary hydrocarbon fluids include,without limitation, natural gas (sweet or sour), diesel fuel, gasoline,kerosene, jet fuel, refinery cuts, alkanes containing 1 to 20 carbonatoms, alkenes containing 1 to 20 carbon atoms, alkynes containing 1 to20 carbon atoms, or mixtures or combinations thereof or mixtures orcombinations thereof, where one or more carbon atoms can be replaced bya main group element selected from the group consisting of B, N, O, Si,P, S, Ga and Ge and one or more of the hydrogen atoms can be replaced byF, Cl, Br, I, OR, SR, COOR, CHO, C(O)R, C(O)NH2, C(O)NHR, C(O)NRR′, orother similar monovalent groups, where R and R′ are the same ordifferent and are carbyl group having between about 1 to about 16 carbonatoms and where one or more of the carbon atoms and hydrogen atoms canbe replaced as set forth immediately above.

Suitable sulfur-containing components include, without limitation,hydrogen sulfide, alkyl, aryl, alkaryl, and aralkyl sulfide, disulfideand undesirable other sulfur-containing compounds generally found influid.

Preparation and Characterization of the Absorbents andAbsorbent/Absorbed Species Interaction

Single crystals of [VOBDC](H₂BDC)_(0.71) 1 were synthesized directly,where V is vanadium, O is oxygen, BDC is 1,4-benzene dicarboxylate (thedianion of 1,4-benzene dicarboxylic acid), and H₂BDC is 1,4-benzenedicarboxylic acid. [VOBDC](H₂BDC)_(0.71) (1), is the V⁴⁺-analog of thepreviously compound MIL-47 as.⁹ After removal of the guest acidmolecules by heating 1 in air, the resulting VOBDC structure showedsufficient flexibility to undergo single-crystal-to-single-crystaltransformations upon absorption of aniline, thiophene, and acetone fromthe liquid phase. After absorption, we were able to characterize theresulting structure detailing the guest structure, framework-guestinteractions, and framework deformations from single crystal X-raydiffraction data.

We have also observed rapid and highly selective gas phase absorption ofthiophene from methane by VOBDC, a process relevant to desulfurizationof fluids including sulfur-containing components such as hydrocarbongases, e.g., natural gas to produce so call sweet natural gas. This andother applications of MOFs were described in a recent review.¹²

The octahedral chain in the structure of [VOBDC](H₂BDC)_(0.71) 1contains a —V═O—V═O— backbone with alternating short and long V—O apicalbonds of the VO₆ octahedra. The equatorial corners of the VO₆ octahedraare shared with the BDC ligands that cross-link the octahedral chains toform 1D rhomb-shape tunnels which are each filled by two columns ofguest H₂BDC. Assuming that the H₂BDC molecules in each column are linkedby hydrogen bonds similar as to the bonding inIn(OH)BDC.(H₂BDC)_(0.75),⁸ and that a H₂BDC molecule has a length of 9.6Å, a theoretical number of 0.71 guest H₂BDC per vanadium atom can bederived from the lattice constants. This guest acid content has beenconfirmed by chemical analysis and structure refinements.¹³

The [M(OH)BDC](H₂BDC)_(x) phases have the same space group symmetry asM(OH)BDC with the guest H₂BDC molecules in neighboring tunnels orientedperpendicular to each other. The same arrangement of the guest moleculesis found in the compound 1, probably because this pattern allows allcolumns of the guest H₂BDC molecules to have favorable π-π interactionswith the framework BDC. The columns of the H₂BDC molecules in differenttunnels of the compound 1 are found disordered over positions shiftedrelative to each other along the tunnel axis in steps of ca. 1.4 Å. Ifviewed along the tunnel axis, the H₂BDC molecules in neighboring tunnelsare oriented perpendicular to each other so that all columns of guestH₂BDC molecules have favorable π-π interactions with the framework BDC.This arrangement of the guest molecules is not compatible, however, withthe symmetry Pnma of the compound 2 that has a mirror plane runningthrough the —O═V—O═V— backbone. The space group symmetry of the compound1 is lowered to the non-centrosymmetric P2₁2₁2₁, which was confirmed bySHG (second harmonic generation) measurements. The SHG efficiencymeasured on a powder sample of the compound 1 is comparable to that ofquartz.

Although the structures of the compound 2 and M(OH)BDC, M=Al³⁺, Cr³⁺ andV³⁺, have the same topology and the same space group Pnma, they showimportant differences in local symmetry. In the compound 1, the metalatom is located at an inversion center while the symmetry mirror planesare perpendicular to the octahedral chain and pass through the centersof the BDC ligands. In the compound 2, the inversion symmetry center isshifted to the center of the BDC ligand, because the V⁴⁺ ion isdisplaced from the center of a VO₆ octahedron to form a V═O double bond.The mirror plane is parallel to the octahedral chain and runs throughthe —V═O—V═O— backbone. This symmetry difference between the frameworksnaturally leads to different space group symmetries of the correspondingcompounds intercalated by the guest H₂BDC molecules.

By heating the compound 1 in air to remove the guest acid, high qualitysingle crystals of VOBDC 2 identical to MIL-47 were obtained and wereobserved to show single-crystal-to-single-crystal transformations uponabsorption of various guest molecules. Accurate structural data of theguest molecules and framework deformations obtained from single crystalX-ray diffraction data are reported here. The thermal removal of theguest H₂BDC led to crystals of VOBDC 2 suitable for single crystal X-raymeasurement.¹⁴ Our determination of the structure of VOBDC 2 is inagreement with that reported earlier by Férey.⁴

Upon immersing in liquid aniline, thiophene and acetone, the crystals ofthe compound VOBDC 2 as shown in FIG. 1A, are transformed into anintercalation compound [VOBDC](aniline) 3 as shown in FIGS. 1B&C, intoan intercalation compound [VOBDC](thiophene)_(0.91) 4 as shown FIGS.1D&E and into an intercalation compound [VOBDC] (acetone) 5 as shown inFIGS. 1D&G, respectively. The compounds 3, 4, and 5 are transformed fromthe compound 2, without losing their crystallinity of the single crystalpart of each structure. FIG. 1H shows all four compounds 2, 3, 4, and 5,where compounds 3, 4 and 5 are shown with their guest molecule in theirproper orientations.¹⁵

The aniline molecule (ca. 7.5 Å long) is much shorter than H₂BDC, butstill longer than the period (6.8 Å) of the VOBDC framework along thetunnel axis. The intercalated aniline molecules in the compound 3 formangles of ±17° to the tunnel axis, which can be considered as acompromise between adapting to the framework period, maximizing packingefficiency, and facilitating π-π interactions with the framework BDCligands. The shortest distance between the benzene ring center ofaniline and the carbon atoms of the BDC benzene ring is 3.507(1)Å, andthe distance between their benzene ring centers is 4.43(1)Å, whichindicates a π-π interaction with substantial ring-ring offset.¹⁵ The π-πinteractions are complemented by weak C—H . . . π and N—H . . . πinteractions between the aniline molecules and the BDC ligands.¹²

The packing of thiophene molecules in the compound 4 is similar toaniline in the compound 3, but the angles between the thiophenemolecules and the tunnel axis are changed to ±26°, probably due to thesmaller molecular size of thiophene relative to aniline. A clear C—H . .. π interaction between the thiophene molecules and the framework BDCseems to play a major rule in dictating the thiophene orientation.¹⁶ Theoccupancy of the thiophene position was refined to 0.91(1) in agreementwith the absorption measurements as described below. Similar to thecompound 1, the guest molecule packing in the compounds 3 and 4, whichresult from the weak interactions between the guest molecules and thehost framework, is not compatible with the space group symmetry ofVOBDC. The centrosymmetric space group Pnma of VOBDC changes to thechiral space group P2₁2₁2₁ upon loading of the guest aniline orthiophene molecules.

Unlike the aniline and thiophene molecules that form two columns in eachtunnel, the acetone molecules in the compound 5 are stacked into onecolumn along the tunnel axis with an antiparallel packing pattern. Theintermolecular C═O . . . C═O distances between about 3.506(1)Å and about3.510(1)Å within the column indicate weak dipolar carbonyl-carbonylinteractions between the acetone molecules, which probably dictate thepacking pattern.¹⁷ The VOBDC tunnel is too small to host two columns ofthe antiparallel-packed acetone molecules. With only one column ofacetone molecules in each tunnel the framework deforms so that therhomb-shaped tunnel section flattens substantially. The flattening notonly improves packing efficiency of the whole structure but alsofacilitates dipolar interactions between the carbonyl group of acetoneand the carboxylate groups of the framework BDC ligands (C═O . . . CO₂:3.267(1)Å). The packing of the acetone molecules is compatible with thesymmetry of the VOBDC framework, therefore, the compound 5 has the samespace group symmetry as VOBDC, represent by the compound 2.

The VOBDC structure 2 has the most open tunnels. Upon intercalation ofguest molecules, the tunnel opening systematically shrinks, because ofthe interactions between the guest molecules and the host framework.This is illustrated by the ratio of the two diagonals of the tunnelsection which changes from 13.99/16.06 (0.87) in the compound 2 to13.03/16.85 (0.77) in the compound 3, to 12.74/16.88 (0.75) in thecompound 4, to 12.62/17.09 (0.74) in the compound 1, and to 10.21/18.41(0.55) in the compound 5. For comparison, the shrinkage in going fromAl(OH)BDC.H₂BDC to Al(OH)BDC.H₂O is even larger, 19.05/7.78(0.41). Thedeformations are realized mainly through changes of the torsion angleV—O═C—C, which is the most flexible component of the framework. Thepacking density calculated for the guest molecule column of the compound5 is 122.2 Å³ per acetone molecule, which is almost identical to that ofliquid acetone. In contrast, the guest packing densities calculated forthe compound 3 and the compound 4 are both ca. 21% lower than thecorresponding liquid densities of the guest molecules assuming a fulloccupancy, probably because the oriented interactions between the guestmolecules and the framework BDC ligands also dictate the stoichiometryof the intercalated compounds.

Thiophene is also absorbed by VOBDC directly from the gas phase as shownin FIG. 2. Single crystals of VOBDC×0.71H₂BDC were heated on athermo-balance in flowing air to 350° C. to remove the H₂BDC guestmolecules as shown in the top, left plot. After cooling to roomtemperature the gas stream was switched to a 5% CH₄/He stream. The datain FIG. 2 show that methane is not absorbed under these conditions asshown in the bottom, left plot. The gas stream was switched to a 5%CH₄/He stream saturated with thiophene at ambient temperature and apressure of 1 atm (10 kPa at 20° C.). Rapid absorption occurs onexposure to methane/thiophene/He corresponding to the uptake of 0.88molecules of thiophene per VOBDC in agreement with the liquid phaseuptake as shown in the inset plot of FIG. 2. Similar results wereobtained for the uptake of dimethyl sulfide, and thiophene at 1 kPa astabulated in Table 1.

TABLE 1 Gas Phase Adsorption by VOBDC Formula +Δw % Molecules/fu^(a)P^(b) _((kPa)) (CH₃)₂S 34 1.12 66.9 C₄H₄S 31.9 0.88 10 C₄H₄S^(c) 23.40.65 1 ^(a)formula unit; ^(b)partial pressure, ^(c)thiophene at 1 kPa.

The reversibility of thiophene uptake was investigatedthermo-gravimetrically and by X-ray diffraction. A sample was saturatedwith thiophene on a thermobalance following the procedure describedabove. When the sample reached constant weight at ambient temperature,the temperature was raised to 150° C. Thiophene desorbed and the sampleweight returned to its initial value as shown in the top, right andbottom, right plots of FIG. 2. An X-ray powder pattern of the finalsample indicated complete retention of crystallinity.

A single crystal of [VOBDC](thiophene) was heated to 200° C. for 30minutes to remove the thiophene. The results shows that the structurereverted back to space group Pnma and the complete absence of anyelectron density in the channels indicates complete desorption ofthiophene. The lattice parameters are a=6.813(2)Å, b=16.248(4)Å,c=13.749(3)Å indicating a 1% smaller cell volume than of the compound 2suggesting that annealing at >200° C. is necessary to allow theframework to completely relax.

The structural details of the four intercalated compounds presented hereand the selective and reversible removal of sulfur-containing moleculesfrom methane show the importance of non-covalent oriented weakinteractions in the packing of organic molecules within channels of aspecific metal-organic framework. Such interactions, although relativelyweak, can readily cause remarkable deformation and symmetry changes inthe framework, which point to effective ways of manipulating knownmaterials or designing new materials with targeted properties throughintercalation chemistry.

Preparation and Characterization of the Generalized Absorbents andAbsorbent/Absorbed Species Interaction

The metal oxide organic frameworks with the general compositionM(OH)BDC×H₂BDC where BDC=1,4-benzenedicarboxylate (C₈H₄O₄) and H₂BDC isthe corresponding acid (C₈H₆O₄) were first synthesized by Férey andco-workers who described in a series of papers the synthesis ofcompounds where M=Al, V, Cr, Fe. All of the compounds with the exceptionof V(III) OHBDC were obtained in polycrystalline form.^(4,5,6,9a,18) Inrecent work, we have extended the class to include single crystals ofAl(OH)BDC×0.7H₂BDC,⁷ In(OH)BDC×0.75H₂BDC,⁹ Fe(OH)BDC pyridine,⁸Fe(DMF)BDC,⁸ andM(III)VO[Fe_(0.28)V_(0.72)OH_(0.8)(NH₄)_(0.2)(C₈H₄O₄)]×0.53 (C₈H₆O₄).¹⁰The synthesis of the Fe,V compound and Férey's observation⁴ that theV(III) compound can be oxidized to V(IV) suggest the possibility ofmaking V(IV)OBDC, directly, which we described above.

Referring now to FIG. 3, the structure of Al(OH)(C₈H₄O₄)×_(0.7)(C₈H₆O₄)6, which was recently determined by single crystal X-ray diffraction isshown. The Al³⁺ is coordinated to six oxygen atoms in distortedoctahedral geometry and the octahedral Al—O centers are linked bysharing trans hydroxyl groups forming Al—OH—Al chains. The Al—OH—Alchains are bent with an angle of ˜129°. The oxygen atoms of the BDCgroups occupy the equatorial positions of the octahedra. The BDC ligandsbridge the chains to form a three dimensional framework with largediamond shaped channels parallel to the b axis as shown in FIG. 3.

As synthesized, the channels of Al(OH)(C₈H₄O₄)×_(0.7)(C₈H₆O₄) 6 arefilled with H₂BDC guest molecules that can be removed by heating to atemperature between about 380° C. and about 400° C. After removal of theguest molecules, one water molecule is absorbed on exposure toatmosphere at room temperature to give Al(OH)(C₈H₄O₄)×H₂O 7; the watermolecules are located at the center of the channels.

Sorption Chemistry

The sorption behavior of the M(OH)BDC compounds has not been studied indetail for applications and is presently not well understood. Thesorption chemistry of these materials is unusual and falls between thebehavior of rigid three-dimensional host lattices and layer structuresthat can expand infinitely in a direction perpendicular to the layers.In the BDC compounds, the expansion is constrained so that the maximumarea for a guest molecule is proportional to the square of the distancebetween metal oxide chains and decreases as the angle of the diamonddecreases of the structure shown in FIG. 3.

The table summarizes some of the known sorbates based on our work and onliterature data. The first thing to note is the paucity of data and thesecond is that insufficient data is available to discern systematictrends; there are no sorption isotherms available. The known sorbatesinclude hydrogen bond acceptors, aromatics, and others. The energeticsof sorption are determined by the guest-host interactions, mainlyhydrogen bonding with the framework OH groups and π-π or C—H πinteractions with the bridging ligands, and by guest-guest interactionswhich may similarly be due to hydrogen bond or π-π interactions. Theframework Al—OH groups are only weakly (if at all) acidic. The strongestacceptors like water and DMF form hydrogen bonds, but because of π-πinteractions M(OH)BDC readily absorb mesitylene, thiophene, and pyridineas shown in the data tabulated in Table 2.

TABLE 2 Adsorption by M(OH)BDC of Various Compounds Compound SorbateAl(OH)BDC H₂BDC H₂O pyridine thiophene n-octane H₂ V(OH)BDC H₂BDC H₂Odiethyl- mesitylene 2-Me-1- ether propanol Cr(OH)BDC H₂BDC H₂O DMF H₂Fe(OH)NDC pyridine Al(OH)NDC H₂O DMF

EXPERIMENTS OF THE INVENTION Examples

The following examples are included for the sake of the completeness ofthe disclosure and to illustrate the present invention, but in no wayare these examples included for the sake of limiting the scope orteaching of this invention.

Example 1

The compound 1 was synthesized by hydrothermal reaction from a mixtureof VO₂, HCl, 1,4-benzene dicarboxylic acid (H₂BDC) and H₂O with molarratios of 1:2:0.5:770. The mixture was heated at 220° C. in a sealedTeflon vessel for 3 days. Red brown prisms of the compound 1 wererecovered as a major phase by vacuum filtering and drying in air,together with dark green impurities that were easily removed by washingwith methanol. For the absorption measurements, red prism crystals ofVOBDC×0.71H₂BDC represented by the compound 1 were heated in air to 350°C. using a 3° C. min⁻¹ heat-up rate to form VOBDC represented by thecompound 2. Intercalation experiments were carried out by immersingcrystals of the compound 2 in liquid aniline, thiophene and acetone. Forgas phase absorption, crystals of the compound 1 were heated on athermobalance to 350° C. in air to remove H₂BDC. The sample wasmaintained at constant temperature for 30 minutes and then cooled to 28°C. When the weight was constant at 28° C., the air flow was switched to5% methane in He. After the weight became constant, the flow of 5%methane in He was passed through a bubbler containing liquid (CH₃)₂S.After a short time, the weight of VOBDC increased dramatically.

Example 2

This example illustrates the synthesis of VOBDC by three differentmethods.

A mixture of VO₂, HCl, H₂BDC, and H₂O in the molar ratios 1:2:0.86:32were placed in a Teflon lined steel autoclave. The mixture was heated at220° C. in the sealed vessel for 6 d and then cooled to ambienttemperature. Red brown prism-shaped crystals of VOBDC bigger than 500μare obtained in >60% yield, together with a dark green vanadiumcompound, which can be washed out easily by methanol.

A second synthesis used the same reaction conditions, but differentstarting reagents namely VOSO₄×3H₂O, (NH₄)₂BDC and H₂O in the ratios1:1:65. The product in the form of brown needles, is obtained in morethan 95% yield.

In both of the syntheses described above the product is obtained in theform of VOBDC×H₂BDC. The free acid is then removed by heating to 340° C.in air to obtain VOBDC.

A third synthesis was developed at lower reaction temperature and at 1atmosphere pressure to eliminate the need for pressure vessels in scaleup. The reactants VOSO₄×3H₂O (2 mmol), (NH₄)₂BDC (2 mmol), and DMF 20 mLwere transferred into a round bottomed flask, which was fitted with acondenser. The mixture was heated with stirring at 160° C. for 3 daysusing an oil bath. A yellow brown powder was precipitated from thesolution, filtered and washed with methanol. The product was confirmedto be VOBDC without extra acid molecules and requires no furthertreatment before use.

Example 3

This example illustrates the adsorption of thiophene from the gas phaseby VOBDC.

Red prism crystals of VOBDC×H₂BDC were heated on a thermobalance in airto 350° C. using a 3° C. min⁻¹ heat-up rate. The temperature wasmaintained at constant temperature for 30 minutes and then cooled toroom temperature, 28° C. When the weight was constant at 28° C., the airflow was switched to 5% methane in He. After the weight became constant,the flow of 5% methane in He was passed through a bubbler containingliquid (CH₃)₂S. After a short time, the weight of VOBDC increaseddramatically. After 1.5 minutes, the weight change saturated. Theincrease of 34%, corresponds to the adsorption of 1.25 molecules of(CH₃)₂S. These results are shown graphically in FIG. 4.

Example 4

The same procedure was used as in Example 3 except that dimethyl sulfidereplaced thiophene. These results are shown graphically in FIG. 5.

Example 5

This example illustrates the adsorption of thiophene from the gas phaseby VOBDC.

A 5 cc/min flow of 5% methane in He balance flow was passed through abubbler containing thiophene. The exit stream was mixed with 90 cc/min5% methane in He and then passed into the thermobalance. At the lowerthiophene partial pressure compare to that used in Example 3, a longertime (26 min) was needed to reach constant weight and a smaller weightuptake was observed. A-6(R-30). These results are shown graphically inFIG. 6.

Example 6

The same procedure was used as in Example 4 except that toluene replaceddimethyl sulfide. P-59-1-2(27). These results are shown graphically inFIG. 7.

Example 7

The same procedure was used as in Example 4 except that octane replaceddimethyl sulfide. A-4-1(R-27). These results are shown graphically inFIG. 8.

Example 8

The table summarizes the weight changes and time to equilibrium forExamples 3-7. Data for hexadecane are also given in the Table 3 obtainedusing conditions of Example 3. In this case the time to reach saturationis much longer (>13 h).

TABLE 3 Gas Phase Adsorption using VOBDC Example # Adsorbate Formula +Δw% Time (min) 3 Dimethyl Sulfide (CH₃)₂S 34 1.5 4 Thiophene C₄H₄S 31.9 35 Thiophene C₄H₄S 23.4 26 6 Toluene C₆H₅CH₃ 26 14 7 Octane C₈H₈ 21 34 8Hexadecane C₁₆H₃₄ 12.5 >13 h

Example 9

This example illustrates the liquid phase adsorption of thiophene froman octane sample.

VOBDC.xH₂BDC red crystals were ground and heated at 400° C. for 10 h inair to remove the guest H₂BDC molecules. A sample of VOBDC (0.5 g) wasplaced in a flask, and 15 mL of a solution of 2000 ppm of thiophene inoctane added. The mixture was stirred and heated to 60° C. using an oilbath. Samples of the supernatant liquid were remove at regular intervalsand analyzed using gas chromatography. A Shimadzu (SSI) GasChromatograph 2010 used to measure the thiophene contents of the sampleswas calibrated by standard solutions of thiophene in octane as tabulatedin Table 4. These results are also shown graphically in FIG. 9.

TABLE 4 VOBDC Adsorption in 2000 ppm of Thiophene/Octane Solution Samplenumber Time (min) samples taken GC measurement (ppmw) 0 0 2000 1 40 15062 75 821 3 132 640 4 220 574 5 280 375

Example 10

A 0.5 g sample of VOBDC was added to 60 ml of octane containing 100 ppmof thiophene. Samples of the supernatant liquid were remove at regularintervals and analyzed using gas chromatography. A Shimadzu (SSI) GasChromatograph 2010 used to measure the thiophene contents of the sampleswas calibrated by standard solutions of thiophene in octane as tabulatedin Table 5.

TABLE 5 VOBDC Adsorption in 2000 ppm of Thiophene/Octane Solution Samplenumber Time (min) GC measurement (ppm) 0 0 93 1 10 85 2 40 83 3 100 81 4160 77These results are also shown graphically in FIG. 10.

APPARATUS OF THE INVENTION

Referring now the FIG. 11, an embodiment of an apparatus for reducingsulfur in a fluid, generally 100, is shown to include a fluid sourcereservoir 102 having an outlet 104 and filled with an input fluid 106,where the input fluid 106 includes sulfur-containing components. Theapparatus 100 also includes a treating vessel 108 having an inlet 110,an interior section 112 filled with a MOADA absorbent 114 of thisinvention and two outlets 116 a&b. The source reservoir outlet 104 isconnected to the treating vessel inlet 110 via a conduit 118 including afirst inline valve 120. The first inline valve 120 is adapted to startor stop the flow of the input fluid 106 from the source reservoir 102 tothe treating vessel 108. The apparatus 100 also includes an outputreservoir 122 including an inlet 124, where the output reservoir 122 isadapted to receive an output fluid 126, where the output fluid includeslower concentrations of the sulfur-containing components. The treatingvessel outlet 116 a is connected to the output reservoir inlet 124 via aconduit 128 including a second inline valve 130. The second inline valve130 is adapted to start or stop the flow of the output fluid 126 fromthe treating vessel 108 to the output reservoir 122. The apparatus 100also includes a sulfur-containing component collection vessel 132including an inlet 134 and adapted to be filled with the absorbedsulfur-containing components 136, where the sulfur-containing componentcollection vessel 132 is adapted to receive the sulfur-containingcomponents 136 absorbed by the MOADA 114 during regeneration of theabsorbent 114. The treating vessel outlet 116 b is connected to thecollection vessel inlet 134 via conduits 138 including a third inlinevalve 140. The third inline valve 140 is adapted to start or stop theflow of the sulfur-containing components 136 from the treating vessel108 to the collection vessel 132 during absorbent 114 regeneration. Itshould be recognized that the input and output reservoirs 102 and 122can be vessels that have an outlet (not shown), a tank car, a pipeline,or any other type of fluid supply system or transport system. It shouldalso be recognized that the collection vessel 132 can be a vessel thathas an outlet, or any other type of vessel such as a tank car, apipeline or any other type of fluid transport system.

The apparatus 100 operates by closing the third valve 140 and openingthe first and second valves 120 and 130 to allow the input fluid 106 toflow through the absorbent 114 in the interior 112 of the treatingvessel 108. As the fluid 106 passes through the interior 112 of thevessel 108, a portion of the sulfur-containing components 136 in thefluid 106 are absorbed by the absorbent 114 to produce the output fluid126. The output fluid 126 is then stored in the output reservoir 122.The size of the interior 112, the fluid flow rate, the temperature andthe pressure in the interior 112 of the vessel 108 are adjusted toachieve a desired reduction in the sulfur-containing components 136 inthe output fluid 126. The input fluid 106 is processes until theabsorbent is near or at its saturation level, at which point the valves120 is closed and remaining fluid is drained from the vessel 108 intothe output reservoir 122. Alternatively, the fluid remaining in thevessel 108 can be forced out by a gas. Once the remaining fluid has beenremoved from the vessel 108, the valve 130 is closed and the valve 140is opened and the vessel 108 is heated to a release temperature. At therelease temperature, the absorbed sulfur-containing components arereleased and flow into the collection reservoir 132. The regenerationprocess can include the use of a gas such as air or an inert gas such asnitrogen to aid in the regeneration process. After the sulfur-containingcomponents have been desorbed, the valve 140 is closed and the valves120 and 130 are opened and more input fluid 106 is processed. Processingis continued until the absorbent is no longer active. However, theinventors believe that the absorbent should work indefinitely if it isnot fouled by materials that are not reversible absorbed. In mostembodiments, the absorbents can be regenerated at least 10 times. Incertain embodiments, the absorbents can be regenerated at least 20. Inother embodiments, the absorbents can be regenerated at least 50. Inother embodiments, the absorbents can be regenerated at least 100. Inother embodiments, the absorbents can be regenerated at least 500. Inother embodiments, the absorbents can be regenerated at least 1000.

Referring now the FIG. 12, an embodiment of an apparatus for reducingsulfur in a fluid, generally 200, is shown to include a fluid sourcereservoir 202 having an outlet 204 and filled with an input fluid 206,where the input fluid 206 includes sulfur-containing components. Theapparatus 200 also includes four treating vessel 208 a-d, each vessel208 a-d have an inlet 210 a-d, an interior section 212 a-d filled with aMOADA absorbent 214 a-d of this invention and two outlets 216 a-d and217 a-d. The source reservoir outlet 204 is connected to the treatingvessel inlets 210 a-d via conduits 218 a-d including first inline valves220 a-d. The first inline valves 220 a-d are adapted to start or stopthe flow of the input fluid from the source reservoir 202 to thetreating vessel 208 a-d. The apparatus 200 also includes an outputreservoir 222 including an inlet 224, where the output reservoir 222 isadapted to receive an output fluid 226, where the output fluid includeslower concentrations of the sulfur-containing components. The treatingvessel outlets 216 a-d are connected to the output reservoir inlet 224via conduit 228 a-d including second inline valves 230 a-d. The secondinline valves 230 a-d is adapted to start or stop the flow of the outputfluid from the treating vessels 208 a-d to the output reservoir 222. Theapparatus 200 also includes a sulfur-containing component collectionvessel 232 including an inlet 234 and filled with the absorbedsulfur-containing components 236, where the sulfur-containing componentcollection vessel 232 is adapted to receive the sulfur-containingcomponents 236 absorbed by the MOADA absorbents 214 a-d duringregeneration of the absorbent 214 a-d. The treating vessel outlets 217a-d are connected to the collection vessel inlet 234 via conduits 238a-d including third inline valves 240 a-d. The third inline valves 240a-d are adapted to start or stop the flow of the sulfur-containingcomponents 236 from the treating vessels 208 a-d to the collectionvessel 232 during absorbent 214 a-d regeneration. It should berecognized that the input and output reservoirs 202 and 222 can bevessels that have an outlet (not shown), a tank car, a pipe-line, or anyother type of fluid supply system. It should also be recognized that thecollection vessel 232 can be a vessel that has an outlet, or any othertype of vessel. It should also be recognized that the absorbents,although generally the same, can be different so that different fluidscan be treated. It should also be recognized that the four vessels canalso be configured so that the input fluid flows through each vesselconsecutively and each vessel can include a different absorbent of thisinvention, where the absorbents can be tailored to remove specificsulfur-containing components.

The apparatus 200 operates by closing the valves 240 a-d and openingsome or all of the first and second valves 220 a-d and 230 a-d to allowthe input fluid 206 to flow through some of all of the absorbent 214 a-din the interiors 212 a-d of the treating vessels 208 a-d. As the fluid206 passes through the interiors 212 a-d of the vessels 208 a-d, aportion of the sulfur-containing components 236 in the fluid 206 areabsorbed by the absorbents 214 a-d to produce the output fluid 226. Theoutput fluid 226 is then stored in the output reservoir 222. The fluidflow rate, the temperature and pressure in the interiors 212 a-d of thevessels 208 a-d are adjusted to achieve a desired reduction in thesulfur-containing components 236 in the input fluid 206. The input fluid206 is processes until the absorbent is near or at its saturation level,at which point some or all of the valves 220 a-d are closed andremaining fluid is drained from the vessels 208 a-d into the outputreservoir 222. Alternatively, the fluid remaining in the vessels 208 a-dcan be forced out by a gas. Once the remaining fluid has been removedfrom the vessels 208 a-d, some of all of the valves 240 a-d are openedand the vessel is heated to a release temperature. At the releasetemperature, the absorbed sulfur-containing components are released andflow into the collection reservoir 232. The regeneration process caninclude the use of a gas such as air or an inert gas such as nitrogen toaid in the regeneration process. After the sulfur-containing componentshave been desorbed, some or all of the valve 240 a-d are closed and someor all of the valves 220 a-d and 230 a-d are opened and more input fluid206 is processed. Processing is continued until the absorbent is longeractive. However, the inventors believe that the absorbent should workdefinitely if it is not fouled by materials that are not reversibleabsorbed. The absorbents can be regenerated at least 10 times. Incertain embodiments, the absorbents can be regenerated at least 20. Inother embodiments, the absorbents can be regenerated at least 50. Inother embodiments, the absorbents can be regenerated at least 100. Inother embodiments, the absorbents can be regenerated at least 500. Inother embodiments, the absorbents can be regenerated at least 1000.

The system 200 is designed to run on a semi-continuous and/or continuousbecause one or more of the vessels 208 a-d can be processing fluid,while one or more of the vessels 208 a-d are being regenerated. Themethod operates by causing valves to switch the flow of the input fluidbetween vessels so that fluid can be processed on essentially acontinuous basis.

Referring now the FIG. 13, an embodiment of a fluid bed apparatus forreducing sulfur in a fluid, generally 300, is shown to include a fluidbed treating column 302. The column 302 includes a fluid inlet 304, afluid outlet 306, an absorbent inlet 308, an absorbent outlet 310 and ascreen 312. The screen 312 is adapted to prevent the absorbent particles318 from falling into a lower section 314 of the column 302. The column302 also includes a fluidized absorbent section 316 including thefluidized absorbent particles 318 and a top section 320, where treatedfluid free of the absorbent particles 318 proceeds upward and out of thecolumn 302 via the fluid outlet 306. The fluid inlet 304 is connected toan inlet fluid handling system (not shown) and the fluid outlet 306 isconnected to an output fluid handling system (not shown). The absorbentoutlet 310 is connected to a regenerator 322 via a first conduit 324 andthe regenerator 322 is connected to the absorbent inlet 308 via a secondconduit 326. As the absorbent particles 318 are circulated from thetreating column 302 to the regenerator 322, where the absorbedsulfur-containing components absorbed by the absorbent particles 318 inthe fluidized absorbent section 316 of the column 302 are desorbed. Theflow rate of the absorbent, its size and shape, the flow rate of thefluid, the size, temperature and pressure of the treating column and thesize, temperature and pressure of the regenerator are adjusted so that adesired reduction in sulfur-containing components can be achieved. Theregenerator 322 is connected to a sulfur-containing component collectionvessel 328 via a conduit 330. The apparatus 300 is designed to beoperated on a continuous basis with absorbent being added and withdrawnas needed.

Inlet fluid enters the apparatus 300 on a continuous basis through theinlet fluid inlet 304. The fluid travels up the column 302 as indicatedby the heavy grey arrows. As the fluid flow up, it passes through thescreen 312, with sufficient velocity or flow rate to suspend theabsorbent particles 318 in the fluid. Generally, the fluid is a gas, butthe fluid can be a gas liquid mixture provided that the particlefluidization is achieved. In the absorbent fluidized section,sulfur-containing components in the inlet fluid are absorbed by theabsorbent, producing an output fluid with lower concentrations of thesulfur-containing components. The output fluid then flows upward intothe upper section 320 of the column which due to column conditions issubstantially fee of absorbent particles 318 and exits the column 302via the fluid outlet 306. Simultaneously, regenerated or fresh absorbentparticles 318 are being fed into the column 302 via the absorbent inlet308 and spent absorbent is withdrawn via the absorbent outlet 310 asshown by the heavy black arrows. The spent absorbent 318 is regeneratedin the regenerator 322, where it is heated to desorb the absorbedsulfur-containing components, which are collected in the collector 328.The regenerated absorbent 318 is then fed back into the column 302 asshown by the heavy black arrows.

Referring now the FIG. 14, an embodiment of a moving bed apparatus forreducing sulfur in a fluid, generally 400, is shown to include a movingbed treating column 402. The column 402 includes a fluid inlet 404, afluid outlet 406, an absorbent inlet 408, an absorbent outlet 410 havinga collector 412 and screens 414. The screens 414 are adapted to preventan absorbent 416 from falling into a lower section 418 of the column402. The column 402 also includes a moving absorbent section 420including the absorbent 416. The fluid inlet 404 is connected to aninput fluid handling system (not shown) and the fluid outlet 406 isconnected to an output fluid handling system (not shown). The absorbentoutlet 410 is connected to a regenerator 422 via a first conduit 424 andthe regenerator 422 is connected to the absorbent inlet 408 via a secondconduit 426. As the absorbent 416 is circulated from the treating column402 to the regenerator 422 as shown by the heavy black arrows, theabsorbed sulfur-containing components absorbed by the absorbent 416 inthe moving absorbent section 420 of the column 402 are desorbed in theregenerator 422. The flow rate of the absorbent, its size and shape, theflow rate of the fluid, the size, temperature and pressure of thetreating column and the size, temperature and pressure of theregenerator are adjusted so that a desired reduction insulfur-containing components can be achieved. The regenerator 422 isconnected to a sulfur-containing component collection column 428 via aconduit 430. The apparatus 400 is designed to be operated on acontinuous basis with absorbent being added and withdrawn as needed. Themoving bed apparatus 400 operates in a manner analogous to the fluid bedapparatus 300.

Referring now the FIG. 15A, an embodiment of a gas treating apparatusfor reducing sulfur in a gas, generally 500, is shown to include a gascylinder 502. The cylinder 502 includes a valve 504. The apparatus 500also includes a cartridge 506 including an inlet 508, an outlet 510, anabsorbent 512 and an indicator 514. The cylinder valve 504 is connectedto the cartridge inlet 508 via a first conduit 516. The cartridge outlet510 is connected to a system 518 at an inlet 520 via a second conduit522, where the system 518 adapted to use the gas after is passes throughabsorbent 512 in the cartridge 506.

Referring now the FIG. 15B, an embodiment of a fuel treating apparatusfor reducing sulfur in a fuel, generally 550, is shown to include a fuelreservoir or tank 552. The tank 552 includes an outlet 554. Theapparatus 550 also includes a cartridge 556 including an inlet 558, anoutlet 560, an absorbent 562 and an indicator 564. The reservoir or tankoutlet 554 is connected to the cartridge inlet 558 via a first conduit566. The cartridge outlet 560 is connected to a fuel consuming system568 at an inlet 570 via a second conduit 572, where the system 568adapted to use the fuel after is passes through absorbent 562 in thecartridge 556. The fuel consuming system 568 can be an internalcombustion engine, a fuel power generator, or any other system thatconsumes a fuel that can include various levels of undesirablesulfur-containing components.

REFERENCES CITED IN THE INVENTION

The following references were cited in the application:

-   1 a) D. W. Breck, Zeolite Molecular Sieves, John Wiley & Sons: New    York, 1974; b) M. E. Davis, Nature 2002, 417, 813; c) H. van    Koningsveld, F. Tuinstra, H. van Bekkum, J. C. Jansen, Acta    Crystallogr. 1989, B45, 423; d) G. Binder, L. Scandella, J.    Kritzenberger, J. Gobrecht, J. H. Koegler, R. J. Prins, Phys.    Chem. B. 1997, 101, 483; e) E. Y. Choi, Y. Kim, K. J. Seff, J. Phys.    Chem. B. 2002, 106, 5827; f) C. A. Fyfe, A. C. Diaz, H.    Grondey, A. R. Lewis, H. J. Forster, J. Am. Chem. Soc. 2005, 127,    7543.-   2 M. S. Whittingham, A. J. Jacobson, Intercalation Chemistry,    Academic Press: New York, 1982.-   3 a) C. J. Kepert, M. J. Rosseinsky, Chem. Commun. 1999, 375. b) H.    Li, M. Eddaoudi, M. O'Keeffe, O. M. Yaghi, Nature 1999, 402,    276; c) K. Biradha, M. Fujita, Angew. Chem. 2002, 114, 3542; Angew.    Chem., Int. Ed. 2002, 41, 3392; d) M. P. Suh, J. W. Ko, H. J.    Choi, J. Am. Chem. Soc. 2002, 124, 10976; e) S. Takamizawa, E.    Nakata, H. Yokoyama, K. Mochizuki, W. Mori, Angew. Chem. 2003, 115,    4467; Angew. Chem., Int. Ed. 2003, 42, 4331; f) B. F. Abrahams, M.    Moylan, S. D. Orchard, R. Robson, Angew. Chem. 2003, 115, 1892;    Angew. Chem., Int. Ed. 2003, 42, 1848; g) B. Rather, M. J.    Zaworotko, Chem. Commun. 2003, 830; h) S. Takamizawa, E. Nakata, T.    Saito, Angew. Chem. 2004, 116, 1392; Angew. Chem., Int. Ed. 2004,    43, 1368; i) S. Kitagawa, R. Kitaura, S, Noro, Angew. Chem. 2004,    116, 2388; Angew. Chem., Int. Ed. 2004, 43, 2234; j) S. Kitagawa, K.    Uemura, Chem. Soc. Rev. 2005, 34, 109; k) A. J. Fletcher, E. J.    Cussen, D. Bradshaw, M. J. Rosseinsky, K. M. Thomas, J. Am. Chem.    Soc. 2004, 126, 9750.-   4 K. Barthelet, J. Marrot, D. Riou, G. Férey, Angew. Chem. 2002,    114, 291; Angew. Chem., Int. Ed. 2002, 41, 281.-   5 a) F. Millange, C. Serre, G. Férey, Chem. Commun. 2002, 822; b) C.    Serre, F. Millange, C. Thouvenot, M. Nogues, G. Marsolier, D.    Louér, G. Férey, J. Am. Chem. Soc. 2002, 124, 13519.-   6 T. Loiseau, C. Serre, C. Huguenard, G. Fink, F. Taulelle, M.    Henry, T. Bataille, G. Férey, Chem.-Eur. J. 2004, 10, 1373.-   7 a) T. R. Whitfield, X. Wang, L. Liu, A. J. Jacobson, Solid State    Sci. 2004, 7, 1096; b) T. R. Whitfield, X. Wang, A. J. Jacobson,    Mater. Res. Soc. Symp. Proc. 2003, 755, 191.-   8 E. V. Anokhina, M. Vougo-Zanda, X. Wang, A. J. Jacobson, J. Am.    Chem. Soc. 2005, 127, 15001.-   9 a) G. Férey, M. Latroche, C. Serre, F. Millange, T. Loiseau, A.    Percheron-Guégan, Chem. Commun. 2003, 2976; b) N. L. Rosi, J.    Eckert, M. Eddaoudi, D. T. Vodak, J. Kim, M. O'Keeffe, O. M. Yaghi,    Science 2003, 300, 1127.-   10 a) D. N. Dybtsev, H. Chun, S. H. Yoon, D. Kim, K. Kim, J. Am.    Chem. Soc. 2004, 126, 32; b) A. C. Sudik, A. R. Millward, N. W.    Ockwig, A. P. Cöte, J. Kim, O. M. Yaghi, J. Am. Chem. Soc. 2005,    127, 7110; c) L. Pan, K. M. Adams, H.; X. Wang, C. Zheng, Y.    Hattori, K. Kaneko, J. Am. Chem. Soc. 2003, 125, 3062.-   11 a) S. Bourrelly, P. L. Llewellyn, C. Serre, F. Millange, T.    Loiseau, G. Férey, J. Am. Chem. Soc. 2005, 127, 13519; b) K. Seki,    Phys. Chem. Chem. Phys. 2002, 4, 1968; c) T. Duren, L.    Sarkisov, O. M. Yaghi, R. Q. Snurr, Langmuir 2004, 20, 2683.-   12 U. Mueller, M. Schubert, F. Teich, H. Puetter, K.    Schierle-Arndt, J. Pastre J. Mater. Chem. 2006, 16, 626.-   13 Elemental analysis results for 1: V, 14.8% obs. (14.6% calc.); C,    47.10% obs. (47.08% calc.); H, 2.68% obs. (2.37% calc.). Crystal    data for 1: space group P2₁2₁2₁, a=6.8094(3), b=12.4220(6),    c=17.1733(8) A, V=1452.6(1) Å³, Z=4, T=223 K, d_(calc)=1.593 g cm⁻³.    Single crystal data were collected on a Siemens SMART/CCD    diffractometer (14526 reflections total, 3498 unique,    R_(int)=0.0478). The structure was solved and refined with the    SHELXTL software package. Final refinements converged at R1=0.0394    for all 3498 reflections and 188 parameters.-   14 Thermogravimetric analyses of 1 carried out in air at 3° C./min    showed two weight-loss events. The first between 320 and 400° C.    corresponds to the loss of the guest H₂BDC. The second between 440    and 480° C. corresponds to the loss of framework BDC. A sample    heated at 390° C. for 10 h was confirmed to be identical to MIL-47    by IR (disappearance of the band at ca. 1700 cm⁻¹ characteristic of    free —C═O species) and single crystal X-ray diffraction (VOBDC, 2:    space group Pnma, a=6.8249(8), b=16.073(2), c=13.995(2), T=293 K,    d_(calc)=1.000 g cm⁻³, R1=0.0443 for all 1904 unique reflections and    67 parameters).-   14 After immersing the VOBDC crystals in the corresponding guest    liquid in air at room temperature for ca. 1 h, a suitable crystal    for each intercalation phase was selected and sealed in a capillary    together with the guest liquid in air and mounted on a Siemens    SMART/CCD diffractometer for X-ray data collection. Crystal data for    3: space group P2₁2₁2₁, a=6.785(1), b=13.031(2), c=16.851(2) Å,    V=1489.8(4) Å³, Z=4, T=223 K, d_(calc)=1.445 g cm⁻³. 12940    reflections total, 3511 unique, R_(int)=0.0698. R1=0.0394 for all    3511 unique reflections and 180 parameters. Crystal data for 4:    space group P2₁2₁2₁, a=6.786(1), b=12.618(2), c=17.086(3) A,    V=1463.0(4) Å³, Z=4, T=223 K, d_(calc)=1.503 g cm⁻³. 8691    reflections total, 3368 unique, R_(int)=0.0641. R1=0.0695 for all    3368 unique reflections and 174 parameters. Crystal data for 5:    space group Pnma, a=6.796(3), b=18.410(8), c=10.214(4) Å,    V=1278.0(9) Å³, Z=4, T=223 K, d_(calc)=1.431 g cm⁻³. 7544    reflections total, 1006 unique, R_(int)=0.2022. R1=0.134 for all    1006 unique reflections and 43 parameters. The crystal quality of 5    is comparatively poor probably because of the large unit cell    changes during intercalation.-   15 C. Janiak, Dalton Trans. 2000, 3885.-   16 H. Suezawa, T. Yoshida, Y. Umezawa, S. Tsuboyama, M. Nishio,    Eur. J. Inorg. Chem. 2002, 3148.-   17 a) D. R. Allan, S. J. Clark, R. M. Ibberson, S. Parsons, C. R.    Pulham, Sawyer, L. Chem. Commun. 1999, 751; b) F. H. Allan, C. A.    Baalham, J. P. M. Lommerse, P. R. Raithby, Acta Cryst. 1998, B54,    320.-   18 Barthelet, K.; Marrot, J.; F ey, G.; Riou, D. VIII(OH){O ₂ C—C ₆    H ₄ —CO ₂}. (HO ₂ C—C ₆ H ₄ —CO ₂ H)_(x)(DMF)_(y)(H ₂ O)_(z) (or    MIL-68), a new vanadocarboxylate with a large pore hybrid topology:    reticular synthesis with infinite inorganic building blocks? Chem.    Commun. 2004, 520-521.

All references cited herein are incorporated by reference. Although theinvention has been disclosed with reference to its preferredembodiments, from reading this description those of skill in the art mayappreciate changes and modification that may be made which do not departfrom the scope and spirit of the invention as described above andclaimed hereafter.

1. An absorbent composition for desulfurizing a fluid comprising: atleast one compound of a class of porous metal organic compounds of thegeneral formula MOADA, where M is a tetravalent metal or a mixture oftetravalent metals, O is an oxygen atom, and ADA is a dianion of adicarboxylic acid (H₂ADA), where the compounds selectively andreversibly adsorb sulfur-containing components in the fluid.
 2. Thecomposition of claim 1, wherein the fluid is a gas, a liquid or amixture thereof.
 3. The composition of claim 1, wherein the fluid is aas hydrocarbon fluids.
 4. The composition of claim 1, wherein thecompounds are capable of absorbing sulfur-containing components at atotal pressure of 1 atmosphere at ambient temperature.
 5. Thecomposition of claim 1, wherein the hydrocarbon fluid is a fuel.
 6. Thecomposition of claim 1, wherein the fluid is selected from the groupconsisting of water, chemical gases and/or liquids, hydrocarbon gasesand/or liquids, biological gases and/or liquids, biochemical gasesand/or liquids, and mixtures or combinations thereof.
 7. The compositionof claim 1, wherein the metal atom is selected from the group consistingof aluminum (Al), vanadium (V), chromium (Cr), iron (Fe), titanium (Ti),zirconium (Zr), hafnium (Hf), cerium (Ce), and mixtures thereof.
 8. Thecomposition of claim 7, wherein the metal atom is V is vanadium.
 9. Thecomposition of claim 1, wherein the dicarboxylic acid dianion isselected from the group consisting of aryl dicarboxylic acids, alkaryldicarboxylic acids and mixtures thereof.
 10. The composition of claim 9,wherein the dicarboxylic acid dianion is selected from the groupconsisting of 1,4-benzene dicarboxylic acid (terephthalic acid),1,3-benzene dicarboxylic acid (isophthalic acid), 4,4′-diphenyldicarboxylic acid, 2,5-pyridine dicarboxylic acid, 1,4-naphthylenedicarboxylic acid, 1,5-naphthylene dicarboxylic acid, and mixturesthereof.
 11. The composition of claim 1, wherein the dicarboxylic aciddianion is the dianion of benzene dicarboxylic acid (H₂BDC).
 12. Thecomposition of claim 1, wherein the metal atom is V is vanadium and thedicarboxylic acid dianion is the dianion of benzene dicarboxylic acid(H₂BDC).
 13. A method for removing sulfur from a fluid, comprising thestep of: contacting a fluid including sulfur-containing components withan effective amount of at least one absorbent of the general formulaMOADA, where M is a tetravalent metal or a mixture of tetravalentmetals, O is an oxygen atom and ADA is a dicarboxylic acid dianion,where the effective amount is sufficient to reduce concentrations of thesulfur-containing components in the fluid or to reduce concentrations ofsulfur-containing components in the fluid to desired lowerconcentrations.
 14. The method of claim 13, further comprising the stepof: removing the absorbent from the fluid, and regenerating theabsorbent to recover the absorbed sulfur-containing components and toregenerate the absorbent.
 15. The method of claim 13, further comprisingthe step of: repeating the steps of contacting, removing andregenerating on intermittent, periodical, semi-continuous or continuousbasis.
 16. The method of claim 13, wherein the fluid is a gas, a liquidor a mixture thereof.
 17. The method of claim 13, wherein the fluid is aas hydrocarbon fluids.
 18. The method of claim 13, wherein the compoundsare capable of absorbing sulfur-containing components at a totalpressure of 1 atmosphere at ambient temperature.
 19. The method of claim13, wherein the hydrocarbon fluid is a fuel.
 20. The method of claim 13,wherein the fluid is selected from the group consisting of water,chemical gases and/or liquids, hydrocarbon gases and/or liquids,biological gases and/or liquids, biochemical gases and/or liquids, andmixtures or combinations thereof.
 21. The method of claim 13, whereinthe metal atom is selected from the group consisting of aluminum (Al),vanadium (V), chromium (Cr), iron (Fe), titanium (Ti), zirconium (Zr),hafnium (Hf), cerium (Ce), and mixtures thereof.
 22. The method of claim21, wherein the metal atom is V is vanadium.
 23. The method of claim 13,wherein the dicarboxylic acid dianion is selected from the groupconsisting of aryl dicarboxylic acids, alkaryl dicarboxylic acids andmixtures thereof.
 24. The method of claim 23, wherein the dicarboxylicacid dianion is selected from the group consisting of 1,4-benzenedicarboxylic acid (terephthalic acid), 1,3-benzene dicarboxylic acid(isophthalic acid), 4,4′-diphenyl dicarboxylic acid, 2,5-pyridinedicarboxylic acid, 1,4-naphthylene dicarboxylic acid, 1,5-naphthylenedicarboxylic acid, and mixtures thereof.
 25. The method of claim 13,wherein the dicarboxylic acid dianion is the dianion of benzenedicarboxylic acid (H₂BDC).
 26. The method of claim 13, wherein the metalatom is V is vanadium and the dicarboxylic acid dianion is the dianionof benzene dicarboxylic acid (H₂BDC).
 27. A system for desulfurizingfluid comprising: at least one vessel including at least one absorbentcomprising at least one compound of a class of porous metal organiccompounds of the general formula MOADA, where M is a tetravalent metalor a mixture of tetravalent metals, O is an oxygen atom, and ADA is adianion of a dicarboxylic acid (H₂ADA), where the compounds selectivelyand reversibly adsorb sulfur-containing components in an input fluid; ainput fluid handling system for supplying the input fluid to the atleast one vessel, an output handling system for receiving an outputfluid, where the output fluid includes lower concentrations ofsulfur-containing components, and piping and valves sufficient toconnect the vessels and the handling systems.
 28. The system of claim27, wherein the system is batch system.
 29. The system of claim 27,wherein the system is a fluidized bed system.
 30. The system of claim27, wherein the system is a moving bed system.
 31. The system of claim27, wherein the system is an internal combustion engine.